Heat treatment is generally used to refer to a process of altering the physical, and sometimes even chemical properties of a material. With respect to metallic materials such as steel, heat treatment can be used to improve the mechanical properties of a material. However, in other examples, a metallic material may even be heat treated to lower the mechanical properties as well.
The application of heat treatment to the golf industry is also known in the art. In fact U.S. Pat. No. 2,332,342 to Reach hinted at heat treating the bottom plate of a golf club head to make it more durable against scuffing all the way back in the 1940's. U.S. Pat. No. 8,663,029 to Beach et al. teaches the utilization of heat treatment on a modern day golf club head by heat treating the cast molten steel or even the cast titanium.
These methodologies, although are very capable of changing the physical properties of the material, do not take advantage of heat treating different portions of the golf club head differently to achieve different performance needs of the golf club head at various portions.
Ultimately, despite all of the attempt to improve the performance of a golf club head via heat treatment; none of the prior art references explore the possibility of heat treating different portions of the golf club head differently to achieve different characteristics. Hence, as it can be seen from above, there is a need in the field for a golf club and a method of heat treatment wherein the ultimate result is capable of creating a golf club with different properties at different portions of the golf club head to match the needs of the golf club head to perform differently at different parts.